The field of the invention is chemical processing of the type where a fluid is mixed with one or more solid particles. One such process utilizes biomaterial supports through the interaction of a biologically active chemical held to the surface of the biomaterial support. Another such process is the basic removal of a solid from a liquid. Biomaterial supports may be inorganic or organic and have been made from glass, having a plurality of pores or other chemically active sites on the surface thereof, and such supports have also been made from polymers which have the capability of holding a desired biologically active molecule along the surface of the support material. The term "biomaterial support" as used herein refers to any substance which has the ability to hold substances which enter into or effect a chemical reaction. This ability may be brought about by micro pores on the surface of the material or by a chemical attraction, reaction, or adsorption of molecules on the surface material.
Various biomaterial supports have been found to have the ability to selectively hold and, in some cases, orient chemicals such as enzymes, antibodies, and binding proteins. These adsorbed substances then can become available to bring about a desired chemical reaction. Biomaterial supports having adsorbed substances are particularly useful for carrying out radioimmunoassay techniques. For example, an adsorbed or bonded antibody material is brought into contact with a liquid containing a known quantity of antigen. The radioactive antigen will compete with the unknown quantity of unlabeled antigen to bind to the antibody coupled to the support. After the competitive binding phase, the biomaterial support is removed from the liquid. This removal has, in the past, utilized techniques such as filtration, centrifugation or decantation.
The use of biomaterial supports is applicable to many processes for separating or reacting large numbers of samples and there is thus a desire to automate many such processes in order to carry them out more efficiently. Attempts to bring about automation of such processes have met with numerous obstacles many of which result from the step of separating the biomaterial support from the liquid reactant. Centrifugation requires several separate steps including placing the sample into a centrifuge followed by a decantation or other removal of the liquid from the solid biomaterial support. Also, centrifugation is not capable of distinguishing between a solid biomaterial support and other solid or more dense liquid components which may be present in the treat liquid.
Separation by filtration of numerous individual samples is generally cumbersome and is a difficult to automate procedure. Heretofor it has been necessary to move a liquid through a filter medium. Furthermore, numerous liquids such as fermentation broths contain substances which interfere with rapid and effective filtration. Like centrifugation, filtration is often incapable of separating a biomaterial support solid from other solids. Decantation is likewise a difficult to automate procedure and is thus usually done by hand. The effectiveness of separation by decantation is highly dependant upon operator's skill and this is inherently undesirable when a high degree of accuracy is required.